Electric coil



March 10, 1942. KEILLQR ET AL 2,275,967

ELECTRIC COIL Filed May 16, 1959 INVENTORS ZEJG'EA/EM [6744019.

z/OJEPHN 132565.

@ l WMATTORNEY.

Patented Mar. 10, 1942 ELECTRIC 0011.

Eugene M. Keillor and Joseph W. Hasse, Muskegon, Mich., assignors toAnaconda Wire & Cable Company, New York, N. Y., a corporation 7 ofDelaware Application May 16,1939, Serial no. 273,874

10 Claims.

Our invention relates to coils, such as solenoids and transformer coilsfor electric apparatus, and more particularly to a wrapping or coveringfor coils of the above type, of simple construction and which willadequately protect the coils from moisture or corrosive influence, andfrom dust or dirt.

Solenoids and coils of the above type are commonly made with severallayers of parallel turns of wire insulated by a coating of enamel, orother insulating material. The coils may be wound on any suitable corein successive layers which are separated from each other by inserts 0rlayers of separating material as, for example, paper or similarinsulating material.

Coils constructed in this manner have one end or terminal at the innerpart of the coil and next to the core, and the other end at theperipheral surface. The inner end is generally brought to the outersurface, for example, in parallel spaced relation to the other end andconnected with lead wires.

A coil of the above, or any similar type, is

enclosed by means of our invention in a wrapping which extendsseamlessly around the assembled layers of turns of the coil and joinedwithin the core and protected by a continuous seamless coatingimpervious to water or to moistened and corrosive atmospheres andhermetically sealing the coil.

In accordance with our invention a coil of wire, the ends of which havebeen attached to lead wires and secured in place on the surface of thecoil, is wrapped in a circumferential direction by a sheet of wrappingmaterial, rendered adhesive on its inner surface and projecting sidewisefrom each of the flat sides or ends of the coil. Thereupon theprojecting, parts of this wrapper are folded inwardly over the sides ofthe coil toward the center thereof and thence into the hollow center orcore thereof and thence or otherwise forming a continuous hermeticallysealed coating on the wrapping.

The various features of the inventionare illustrated by way of examplein the accompanying drawing in which Fig. 1' is a side view of a wrappedcoil embodying a preferred form of our invention, parts of the wrapperbeing broken away to show the interior construction.

Fig. 2 is an end view taken partly on the line 2-2 of Fig. 1 of th coilshown in Fig. 1, and

Figs. 3 to 10 inclusive show the various stages of making the coil ofFigs. 1 and 2, these views taken on a somewhat smaller scale.

In the embodiment of the invention shown in the accompanying drawing, acoil or solenoid ll of successive layers of insulated wire is wrapped bya sheet l2 of flexible material. The coil Il may be of any suitable typeand construction, that shown in the drawing being one in whichsuccessive layers l3 of insulated wire are wrapped on a paper core it,each layer of the windings of wire being separated from the nextadjacent windings by sheets l5 of thin separating material, such asglassine paper. I

When a sufiicient number of layers of wire have been formed to give thedesired electric characteristics, the completed coil or solenoid willhave an inner end of wire, such as indicated at It in Fig. 3, which mayextend to one side between the windings and the paper core [4 and anouter end I! extending circumferentially on the outermost separatingsheet I5.

secured adhesively to the inner surface of the hollow core. A hollowtube, closely fitting the inner surface of the coil or its core, is theninserted to finish the wrapping andcover the exposed ends.

If the wrapping material is in a moist or wet condition, it can befolded to conform very closely to the shape of the coil and upon dryingmay shrink to form a very tight wrapping or enclosure, thereafter it.may be rendered waterproof and proof against the entrance of corrosivematerials or atmospheres b dipping it into a bath or solution of asuitable covering material,

To protect the outermost layer of wires, they are wrapped in acircumferential direction by a strip I8 of a material of suitablestrength and toughness as, for example, varnished cambric, the materialbeing wrapped to the position shown in Fig.

Preferably the face of this paper immediately below the terminal. of thewire I! is further protected by a covering of paper l9. To bring the endIB of the coil to the peripheral surface of the coil and in parallelismwith the wire H, a strip 20 of a suitable materiahfsuch as vulcanizedfiber or tough paper, is inserted between the wire l6 and the end of thecoil and then wrapped over one side of the coil and across theperipheral surfac to the position indicated in Fig. 4. The wire endl6'is then brought upwardly over the side of the coil on the strip 20 toa position of parallelism with the wire end I1, and then the wire endsl6 and I! are secured to respective insulated lead wires 2| and 22. Theends thus secured may then be covered by a strip 23 overlying the strip20. The free end of the wrapping strip i8 is then wrapped downwardlyover the lead wires 2| and 22 and the ends of the wires I6 and I1, asindicated in Figs. 5 and 6 to cover and hold the wires, and the end ofthe strip I8 is then secured by a narrow strip 24 of gummed paper, suchas Scotch tape. The coil is now ready to be covered by the .protectivecovering of our invention.

In covering the completed coil, it is wrapped in a circumferentialmanner with a sheet 25 of suitable protective material as, for example,vulcanized fiber having slits or openings 26 and 21 through which thelead wires 2| and 22 extend, as indicated in Fi 7. The outer or free endof the strip, indicated at 28, is preferably brought to a positionimmediately beneath the lead wires 2| and 22 covering the slits 26 and21 and reinforcing the coil at this point with a double thickness of theWrapping material. The wrapping material is rendered adhesive or gummedon its inner surface so that the overlapped end seals by adhesion to thepart of the wrapper it overlaps. The wrap ping sheet 25 is wider thanthe width of the coil and, therefore, extends on each side'as indicatedat 29 and 30.

These projections are then folded over the sides of the coils toward thecenter and pushed into a hollow core, as shown in Fig. 8. material is ina moistened or wet condition and therefore very flexible, it can befolded to conform and fit the coil very closely, .and being adhesive orgummed on its inner surface will adhere to the inner surface of thehollow core. In case a sheet of material, such as wet vulcanized fiberis used, which shrinks on drying, this will tend to form a tautdrum-like covering for the coil. To insure a tight seal of the endportions ll of the wrapping against the inner surface of the hollowcore, the wrapping is preferably pressed tightly against the innersurface of the core by means of a mandrel and the entire coil pressedand heated to dry it on the core. The wrapping may then be finished byinserting a tube 32 within the coil to conform closely to the shape ofthe paper core. This spans the abutting edges of the parts 3| of thewrapping within the core and completes the enclosure.

- The wrapping material may have some resistance to the penetration ofmoisture or corrosive gases, or may be quite permeable thereto, but isprotected against water or the entrance of other corrosive materials bybeing coated with a continuous coatingof waterproof'or water resistantand corrosive resistant composition which thus forms a continuousunbroken or hermetic seal for the entire coil.

This material which may be rendered in aplastic liquid condition bymeans of solvents or heat, may be applied to the coil in any suitablemanner; for example by dipping or spraying.

As indicated in Fig. it is applied by dipping the wrapped coil into abath 33 of the plastic or liquid coating material which has the furtheradvantage of coating the lead wires 2| and 22 for a distance from thecoil II with a coating that is continuous with that of the coil.

.The wrapping of our invention may be applied to a wide variety ofcoils, such as the secondaries or primaries of transformers, or torandom wrapped coils, such as used for dynamic speaker field coils.These coils may be moistureproofed in any suitable way, as washeretofore practiced. Such moistureproofing is generally not sufficientto form a complete waterproofing of the coils and complete protectionagainst the entrance of If the corrosive agents. The final completewrapping and coating provided by our invention affords more effectiveand additional protection against the entrance of such agents.

- Vulcanized fiber has been mentioned as the wrapping material, but itwill be understood that various other wrapping materials such asleatheroid, varnished cambric, varnished silkvinylite film, or anypermissible digested cellulose film or sheet may be employed. A widevariety of varnishes or coating materials may be used for the finalfinish of the wrapping, the selection of the particular varnish orcoating material depending upon the uses to which the coil is to besubjected.

While the above construction enables the coil to be enclosed in awaterproof wrapping, it can also be used to hold together a random woundcoil such as a dynamic speaker field coil, or to prevent the entrance offoreign particles into the winding. In such cases the final coating neednot be waterproof or moistureproof.

Various modifications may be made by those skilled in the art withoutdeparting from the invention as defined in the appended claims.

What we claim is: v

1. A coil of the type described which comprises concentric turns of wireon a hollow core and a covering comprising a continuous sheet ofvulcanized fibre wrapped circumferentially about said coil to form acomplete wrapping and extending over the sides of the coil, and into thehollow core thereof and being shrunk and pressed about said coil and acontinuous coating of scal ing material enclosing said wrapping.

2. A coil of the type described which comprises concentric turns of wireon a hollow core and a covering comprising a sheet of vulcanized fibrewrapped circumferentially about said coil and extending sidewise overthe sides of said coil and into the hollow core thereof, a tube in saidcore having its outer surface against the inturned parts of said sheetand a continuous coating of sealing material enclosing the wrapped sheetand tube.

3. A coil of the type described which comprises concentric turns of wireon ahollow core, lead wires extending from the circumference of saidcoil and connected to opposite ends of said wire and a coveringcomprising a continuous sheet of material through which said lead wiresextend near one end of said sheet, said sheet being wrappedcircumferentially about said coil with the opposite end thereofunderlying the projecting ends of said lead wires, said sheet projectingover the ends of said coil centrally to and into the hollow corethereof, a tube inserted into said core to cover the ends of saidwrapped sheet, said sheet being shrunk and pressed about said coils anda continuous coating of waterproofing material hermetically sealing saidwrapping of sheet and tube and the lead wires projecting therefrom.

4. A method of sealing a coil of the type described which compriseswrapping said coil circumferentially with a wet sheet of wrappingmaterial which shrinks on drying to completely enclose said coil, saidsheet projecting over the sides of said coil, folding the projectingends of said sheet over said sides of said coil centrally toward andinto the core thereof while wet, drying said sheet to shrink it on saidcoil and coating said dried wrapping in acoating of sealing material toform a continuous hermetic seal therefor.

, 5. A method of enclosing a coil of the type described which compriseswrapping said coil circumferentially with a wet sheet of vulcanizedfibre to completely enclose said coil and with ends ofsaidsheetprojecting over the sides of said coil, folding said projecting endstoward and into the core of said coil, inserting a tube into said coreand drying and coating the completed wrapping with a moisture-proofingmamoistureproofing said wrapping to hermetically seal the coil therein.

'7. A coil of the type described which comprises concentric coils ofwires on a hollow core and having lead wires extending from thecircumferential surface of said coil and a covering comprising acontinuous sheet of vulcanized fibre wrapped circumferentially aboutsaid coil with one end underlying said lead wires and the opposite endoverlapping said underlyingend, said shet extending from each side ofsaid coil cen trally toward said core and into said core, and a tubularmember in said. core and overlapping the inturned edges of said sheet,said sheet being shrunk onto said coil and moistureproofed.

8. A method of enclosing a coil of the type described which compriseswrapping the. .coil circumferentially with a wet sheet 'of vulcanizedfibre to form a complete circumferential enclosure thereof and with theends of said sheet overlapping and with the sheet projecting overoverlapping and with the sheet projecting over the sides of said coil,folding the projecting ends of said sheet to and into the hollow endsof.

the core of said coil while said sheet is soft and flexible and dryingand treating said sheet to shrink it and render it stiff while pressingit into position about said coil and into said core.

9. A method of enclosing a coil of the type described which compriseswrapping the coil circumferentially. with a wet sheet of vulcanizedfibre to form a complete circumferential enclosure thereof and with theends of said sheet overlapping and with the sheet projecting overthesides of said coil, folding the projecting ends of said sheet to andinto the hollow ends of the core ofsaid coil-while said sheet is softand flexible and drying and treating said sheet to shrink it and renderit stiff while pressing it into position about said coil and into saidcore and inserting a hollow core into the core of said wrapped coil tocover the inturned edges of said wrapped sheet.

10. A method of enclosing a coil of the type described which compriseswrapping the coil circumferentially with a wet sheet of vulcanized fibreto form a complete circumferential enclosure. thereof and with the endsof said sheet the sides of said coil, folding the projecting ends ofsaidsheet to and into the hollow ends of the core of said coil whilesaid sheet is soft and flexible and drying and treating said sheet toshrink it and render it stiff while pressing it into position about saidcoil and into said core,

and immersing said wrapped coil into a waterproofing material tohermetically seal said coil in the wrapped enclosure.

EUGENE M. KEILLOR. I

JOSEPH W. HASSE.

